Fix snapd growpart and final message warnings

[blackboxsw]

rebase merge use individual commits

Proposed Commit Message(s)

• fix(final_message): do not warn on datasourcenone when single ds

  Avoid warning level log "Used fallback datasource" when base configuration defines datasource_list: [ None ].

  Using DataSourceNone in this case is desired behavior.

  Also drop unused is_disconnected property from DataSource which was only used by DataSourceNone in cc_final_message.

  Instead compare based on dsname property.

  Fixes: GH-5192

• fix(growpart): correct growpart log message to include value of mode

Additional Context

Affects snapd UC24 which sets `datasource_list: [ None ]' in some configs

Test Steps

Checklist

• [x] My code follows the process laid out in the documentation
• [ ] I have updated or added any unit tests accordingly
• [ ] I have updated or added any documentation accordingly

Merge type

• [ ] Squash merge using "Proposed Commit Message"
• [x] Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[blackboxsw]

cc: @Meulengracht for snap-related concerns.

[Meulengracht]

Thank you to everyone involved here for getting this ball rolling and fixed so quickly!

[github-actions[bot]]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

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[holmanb]

I have no more updates to make, I'm just setting this to "request changes" to make it more obvious that this is waiting on @blackboxsw right now.

@blackboxsw since this will make DataSourceNone users no longer have a warning message we might want to squeeze this one into 24.2. I'm adding it to the milestone so that it doesn't slip by without a discussion (we can remove it if we decide it's not a priority).